The present invention pertains to a process for printing substrates and substrates printed thereby, and more particularly to a single substrate, repeat-pass printing process and substrates printed thereby.
The ink printing of fabrics, such as woven and nonwoven fabrics, with various patterns and colors is well known. These printed fabrics are then incorporated into various products, such as personal care products. Examples of personal care products include diapers, training pants, incontinence products, and the like. The printed fabrics are primarily intended to aesthetically enhance the appearance of the products.
One problem with current ink printing processes is that the ink or inks can run through, i.e., strikethrough, the fabric, and particularly a low basis weight fabric. Low basis weight fabrics are generally thin, and inherently include a large number of small voids, or a smaller number of larger voids, through which the ink can strike through. The problem with ink strikethrough is that the ink builds up on, for example, an impression cylinder of the printing apparatus. This ink buildup on the impression cylinder results in poor print quality on the fabric, the transfer of ink to the back of the fabric, and poor operating efficiency due to machinery down time required to remove the ink buildup.
This problem becomes even more significant in high speed printing environments, where the ink buildup is accelerated and increases the number of times the machinery needs to be shut down for removal of the buildup. As the shut down times increase, so do waste of material and ink associated with machinery start-up.
One attempt to resolve ink buildup is the use of doctor blades on an impression roll or the like. Although doctor blades remove ink buildup while machinery is operating, their use prematurely wears out the surface of the cylinder or roll supporting the fabric. This, in turn, results in increased costs due to replacing prematurely worn out equipment.
Another attempt to eliminate ink buildup is to run a layer of material between the fabric and impression cylinder. The layer is designed to collect or absorb ink strikethrough and carry it away. This has proved to be costly, since either the layer must be replaced with a new layer, or the layer must be cleaned of the ink before being rerun through the printing apparatus.